Influence of moss crust on the stability of soil aggregates developed in different lithologies in karst area

Abstract: BackgroundThe fragile ecosystem of the Karst region in southwest China makes soil erosion and rock desertification the biggest ecological and environmental problems in the region. As a widely developed surface cover, biological crust plays a key role in the regulation of soil erosion, but the influence of moss crust cover on the distribution and stability of soil aggregates under different lithological conditions is not clear, so we explored the influence of lithology and moss crust cover on the distribution characteristics and stability of soil aggregates, with a view to providing theoretical basis for the prevention and control of soil erosion in karst. MethodsBased on the dolomite and clastic rocks, five levels of crust cover (1%~20%, 20%~40%, 40%~60%, 60%~80%, 80%~100%) were set up, and the bare soil without crust cover was used as the control, and the Le Bissonnais method was used to study the distribution of soil aggregates and their stability characteristics, and the Pearson method and the through-traffic analysis method were used to clarify the correlation between the soil physicochemical properties and the stability of aggregates. The correlation between soil properties and aggregate stability was clarified by Pearson's method and through path analysis, and the main controlling factors affecting the stability of aggregates were clarified. ResultsThe results showed that: 1) soil properties were significantly affected by lithology and crust development (P<0.05), dolomite moss crust-covered soil organic matter content, chalk content and clay content increased by an average of 3.20%、3.44%、27.99% compared with bare soil; and clastic moss crust-covered soil organic matter content, chalk content and clay content increased by an average of 7.70%、8.19%、86.03%.2) Under the LB method, the fast wetting (FW) treatment had the greatest damage to the aggregates, followed by the FW treatment and the FW treatment. destruction, followed by pre-wetting oscillation (WS) treatment, and slow wetting (SW) treatment was the smallest, the maximum destruction mechanism in this watershed was the dissipation effect produced by fast wetting FW during heavy rain or storm, and the agglomerates with 80%~100% crust cover were the best in terms of stability, and the bare soil was the worst.(3) The agglomerates MWD and GMD of dolomite and clastic rock under 80%~100% crust cover were higher than the The remaining cover, and the soil erodibility K value and soil fractal dimension D value were the smallest, indicating that the agglomerate with 80%~100% crust cover had the highest stability and the strongest erosion resistance.4) Correlation analysis showed that the powder grain content, clay content and organic matter content had a significant effect on the soil aggregate stability, and the flux analysis further showed that the mechanical composition was an extremely important influencing factor affecting the stability of the agglomerate. Conclusion The lithology and moss crust cover in karst area significantly affect the aggregate stability, and the higher the moss crust cover, the stronger the aggregate stability and erosion resistance, which is of great significance for the prevention and control of soil erosion and sustainable utilization in karst area.